In the offshore industry, the exploration and production of gas and petroleum is conducted through tubulars of various diameters that are cemented inside each other and extend to a distance below the sea floor, where the production zone is located. When the well is abandoned, the owner of the offshore rig is required to remove the casing at the depth of 20 feet below the mud line. After the casing is cut, the rig owner must cement the plug on the abandoned well to protect the marine life in the surrounding area.
To perform the cutting operation below the mud line, a cutting tool is lowered into the innermost casing, which usually has a relatively small diameter, and severs the tubulars. When the first inside casing is removed, another cutter with greater cutting diameter is lowered inside the pipe and the next diameter conduit is cut in a similar manner. This procedure continues until the multiple tubulars are cut at the required depth.
Conventionally, the industry uses a three-blade cutting tool, which will first cut the 7⅝″ pipe, then another cutting tool that will cut 10¾″, etc. If the inner casing collapses, the job becomes even more complicated and the casing needs to be drilled out or severed by an explosive to remove the smallest diameter casing. The conventional three-blade tool has cutter blades equidistantly spaced about the circumference of the tool body. The distance between the cutter blades in a conventional tool suitable for fitting into the smallest diameter pipe is relatively pipe is relatively small. The cutter blades have to be sufficiently small, as well, to allow lowering into the small diameter innermost tubular. The cutter blades of a conventional tool are often damaged, requiring pulling the tool to the surface and starting the process again. The painstaking process takes several days over the use of conventional tools.
If the inner casing collapsed, it may become completely impossible to mill out the necessary portions of the tubulars. In that case, the casing must be cut from the outside, first excavating the mud around the casing to the required depth and then applying the cutting tool to do the job. Such procedure is also expensive and takes several days.
The present invention contemplates elimination of the drawbacks associated with the prior art and provision of a casing cutter that can be used for cutting multiple tubulars in an efficient manner that allows to save time and expense of the operation.